This is a new issue, started about a week ago and it's making me crazy. Macbook Pro connected to a Thunderbolt Display. Nothing has been updated since this started. Before, when in sleep mode, I just clicked on the mouse button (trackball) and the desktop would be on the display. Now, after sleep, the display lights but is blank, and I have to open and close the MB lid for the desktop to appear. If anyone has any ideas on this I would be grateful.